Study on Stress–Strain and Hot Tearing of Liquid Film Between Single Grains of High-Silicon Aluminum Alloy

Hot tearing is generally believed to be caused by the contraction stress of intergranular liquid film during the late stage of solidification, but previous experimental studies about it were all conducted on polycrystalline samples, which could not accurately reflect the stress–strain characteristics of the intergranular liquid film between two single-crystalline grains. In this study, stress–strain characteristics of the eutectic liquid film between two individual Si crystal grains in a high-silicon Al alloy were investigated through the combination of experimental and numerical simulation for the first time. The results show three key factors that affect the stress–strain characteristics of the intergranular liquid film, and the most significant factor affecting hot tearing is the stretching rate, followed by temperature, and finally is the liquid film thickness. Study conditions were: a temperature of 580 °C, a stretching rate of 2 mm/min, and a thickness of 1mm. Although the liquid film has high maximum rupture stress, the mobility of the liquid film is good enough to promptly feed the cracks formed by liquid film rupture. Therefore, the alloy has the lowest tendency for hot tearing. The simulation results show that the main factor affecting the stress–strain of the liquid film is the interaction between viscous force (F_vis) and capillary force (F_cap).